1. Field of the Invention
The present invention relates to an image capturing apparatus; in particular, to an image capturing apparatus with suppression of image blur and method thereof for suppression of image blur under long exposure time.
2. Description of Related Art
As digital camera technology develops rapidly and extensively, people nowadays pay more and more attention to technologies for suppressing the problem caused by involuntary hand movements (handshake) which may result in blurred images. Currently, technologies for anti-handshake can be generally categorized into two types of mechanisms: optical detector mechanism and software compensation mechanism, respectively.
The principle of optical detector mechanism is to perform process on lens and charge-coupled devices (CCD's), wherein it controls the correction of lens or CCD's through the detection result of a shake detector, so as to compensate the shake caused by the camera itself. In terms of lens control: it, by using the principle of lens floating, detects the shake shift by a shake detector, calculates the shift amount by a shake correcting component, then drives the lens for optical axle correction so as to keep the display stable. The advantage thereof lies in better image quality, but the effect of anti-handshake is not significant (since available space for lens floating is limited). On the other hand, for CCD control mechanism: it similarly employs a shake detector to detect the shake shift, and, by using the principle of mechanical support floating, cancels the image blur caused by handshake through adjusting the position correction of CCD's, in which the effect of anti-handshake thereof is better than the lens control approach, but such design may deteriorate the image quality; meanwhile, this type of anti-handshake mechanism needs to cooperate with CCD's consisting of more pixels to present its usability, otherwise the situation that image is stable but loose or blurred in quality may occur.
However, due to complexity in mechanism design and manufacture cost, the anti-handshake technology in the aforementioned optical detector mechanism is generally applied only to cameras of higher level. Whereas, for cameras of lower level, based on issues such as mechanism design complexity and manufacture cost, the optical detector mechanism is obviously not practical, hence the industry has developed the most commonly used software compensation mechanism (generally referred as electrical anti-handshake).
The essential principle of software compensation mechanism is that it uses a shake detector to record the track of moving or shaking in camera during photography, so as to provide information for performing image restoration process, which forms thus a type of post-process technology for single image formation in image capture of camera. But, the general post-process technology for single image may offer different image restoration quality under different degree of moving, and the image restoration quality obtained may be also affected by noise, leading to unsatisfactory practical effect of image restoration. Additionally, since the said post-process technology uses in general only estimated Point Spread Function (PSF) and the captured image blur to perform clear image restoration process, hence, due to very limited available resources, it needs to rely on complicated algorithm and long-time arithmetic calculations to restore a clearer image. Therefore, regarding to anti-handshake feature and effect in the currently available digital cameras, there is still much to be desired.